A tube or extrusion press configured as a frameless metal extrusion press in which the rod of the press piston is configured as a piston rod, which are located at positions normally occupied by tension rods or columns of the usual press frame and which are connected with the counterbeam, is known from DE 198 35 717 (U.S. Pat. No. 6,082,162) with two such main press cylinders. In order to achieve a high degree of operating efficiency and to minimize dead time, both the take up of the play and the retraction should be carried out with the greatest possible speed, which requires high volumetric flow of the fluids involved. The main cylinders are thus configured with approximately the same stroke volume to both sides of the main press piston and a switchable connection is provided between the partial cylinder compartments on the two sides.
To press a blank, the press piston of the press cylinder supported by the cylinder beam is pressurized and for this purpose the piston rod of the press piston must extend to and be connected with the traveling beam. The press piston with its piston rod is bored to form a passage over a part of the length to constitute a cylinder bore in which a plunger piston extends, the latter being braced against a cover closing the cylinder. The pressurization of the plunger piston allows retraction of the press piston and with it via the piston rod, the traveling beam into the starting position. Further piston and cylinder units are braced against a base frame of this press in order to enable the traveling beam to be displaced over the play or nonload portion of its stroke in a rapid movement.
Apart from the fact that this metal extrusion press brings with it a certain significant expense, numerous components must be mounted on the counterbeam to permit the main cylinder with its piston rod to connect to the traveling beam. This has been found to limit the working range of the metal extrusion press above all in cases in which the extrusion press profile or cross section is not straight but in which the extrusion press profile should be produced with curvatures or radii in different directions (compare EP 0 706 843 B1).